This is not really a pro-backlash nut, but a pro-play nut. But that sounds a bit nuts.
Due to lack of space, couplers etc., i had to place the "anti wobble system" above the x axis mounts.
BOM:
4x M3 screws from original lead screw
4x M3 nuts
1x M8 nut
(Flexible filament)
There are 3 different STLs depending on your M8 nut:
iso4032 - 6.8mm height
din934 - 6.5mm height
iso4035/4036 - 4.0mm height
I used generic TPU from ebay, its quiet flexible but not really elastic.
EDIT:
Looks like thingiverse doesn't support GIFs in preview. So, if you want to see it work you have to click the picture, maximize and then "View Original".